My husband and I took this tour as a way to get some spooky history and to cover the city. Booking was easy and this tour was less expensive than many of the others, which was nice. We decided on the extended tour, which was quite a bit of walking, so we succeeded in seeing many areas of the city. I think the regular hour would have been fine. Since it wasn't a tour that stops at pubs or goes underground, the format of walk-stop-story-walk is probably best in about the span of an hour unless you really want to get extensive into the different areas.
We didn't have anyone else on our tour, which was kind of a bummer. We like meeting other folks and seeing their reactions and conversation, etc. Our guide, Amanda, though was talkative and between stops had a lot to say about the area and city in general.
Overall, it's a good way to get some background, but the hour is probably a sufficient overview. I think you'd cover a lot of ground either way.